JP5058322B2 - Ink for inkjet recording and printing substrate - Google Patents

Description

  The present invention relates to an inkjet recording ink, and more particularly to a pigment-based inkjet recording ink having no color loss and excellent chroma and a printing substrate obtained by inkjet recording using the ink.

Ink-jet printing has made it possible to print with image quality comparable to conventional multicolor printing and color photographic methods, and it is easy to increase speed and multicolor, and when there are few copies, conventional printing methods Compared to the above, the cost is low, and it is becoming widespread in various applications.
Conventionally, when printing by an ink jet method, a recording sheet in which a water-soluble polymer such as polyvinyl alcohol is coated on a sheet to form a receiving layer has been used, and printing with water-based ink has been performed. Because of the use of water, there is no water resistance, and there is a problem that the image quality deteriorates in a high humidity environment or when wet. Further, the ink absorbability is not sufficient, and it is difficult to obtain a clear and highly accurate image.

  In order to solve these problems, a recording sheet in which a receiving layer composed of the water-soluble polymer and fine particles such as silica and alumina is formed has been proposed. Japanese Patent Application Laid-Open No. 62-149475 discloses an average particle diameter. Describes that the use of spherical particles having a particle size of 1 to 50 microns can improve the ink absorptivity without impairing the image quality. Japanese Patent Publication No. 3-24906 describes that a recording medium having a receiving layer containing a cationic hydrated aluminum oxide is suitable for printing with a water-soluble dye ink. Japanese Examined Patent Publication No. 4-19037 describes that a recording medium having a receiving layer containing cationic colloidal silica is suitable for printing with a water-soluble dye ink.

Japanese Patent Publication No. 4-115984 discloses that a recording sheet in which a layer made of porous silica is provided on a layer made of pseudoboehmite alumina has transparency and high ink absorbability. JP-A-6-55829 has a layer of porous silica particles having an average particle diameter of 2 to 50 μm, an average pore diameter of 8 to 50 nm, and a pore volume of 0.8 to 2.5 cc / g. Further, it is described that a recording sheet having a pseudo boehmite porous layer obtained by drying alumina sol as an upper layer has high ink absorbability and good dye stability.
All of the above inks are intended for dye-based inks, but printing with dye-based inks changes color due to contact with ultraviolet light, oxygen, or ozone, i.e., there is no weather resistance or fading, and the color changes over time. There are disadvantages such as decoloring. Such a problem is particularly noticeable when used outdoors.

  On the other hand, although pigment-based inks generally have weather resistance, pigment particles are usually particles having a particle diameter of 10 to 500 nm, and conventional receiving layers do not have pores that can effectively absorb such large particles. Therefore, the pigment particles are not absorbed by the receiving layer and remain on the surface of the receiving layer, resulting in problems that water resistance is insufficient or that the pigment particles are removed due to abrasion and discolored.

  In addition, pigment-based inks are blended with a small amount of resin as a dispersant in order to improve the dispersion stability of pigment particles. For example, JP-A-9-241554 discloses an inkjet recording liquid in which pigment particles and resin particles are dispersed in an aqueous medium containing a water-soluble resin. The total content of the resin particles and the water-soluble resin in the recording liquid is 0.2 to 10% by weight, but since it is used as a dispersant, the total weight ratio of both resins to the pigment particles is about 2. At rest. Furthermore, pigment-based inks have the disadvantage that pigment particles are irregularly shaped, causing irregular reflection on the surface of the particles, and image quality superior in saturation compared to dye-based inks cannot be obtained. .

Japanese Patent Laid-Open No. Sho 62-149475 Japanese Patent Publication No. 3-24906 Japanese Patent Publication No. 4-19037 Japanese Examined Patent Publication No. 4-115984 JP-A-6-55829 JP-A-9-241554

  SUMMARY OF THE INVENTION An object of the present invention is to provide an ink for ink jet recording which has characteristics such as no color fading, a printed image is clear and excellent in saturation.

The present invention is an ink jet recording ink containing 1 to 30% by weight of resin and 0.05 to 10% by weight of colored particles, wherein the weight ratio of resin to colored particles (resin / colored particles) is 2. It exists in the range of 5-25.
The colored particles are preferably porous inorganic oxide fine particles containing pigment particles or a dye.
The resin preferably has an average molecular weight in terms of polyethylene in the range of 2,000 to 100,000.
The printing substrate of the present invention is a printing substrate obtained by ink jet recording using the ink described above, and the colored particles are fixed on the printing substrate by the adhesive force of the resin coated with the colored particles. It is characterized by this.

According to the ink of the present invention, prints and images on the printing substrate do not lose color and are clear and excellent in saturation.

  Hereinafter, preferred embodiments of the present invention will be described. The ink according to the present invention is obtained by dissolving or dispersing a resin and colored particles in water and / or an organic solvent, and is used as a water-based ink or an oil-based ink.

(1) Resin As the resin used in the present invention, a conventionally known water-soluble resin or oil-soluble resin can be used.
As the water-soluble resin, polyvinyl alcohol resin, polyester resin, water-soluble silicone-modified alkyd resin, water-soluble modified epoxy resin, water-soluble nylon resin, water-soluble melamine resin and the like are preferably used.
As the oil-soluble resin, a polyester resin, an acrylic resin, a methacrylic resin, or the like is preferably used.
When these resins are used, the water-soluble resin is preferably used as a water-based ink using water as a main solvent, and the oil-soluble resin is preferably used as an oil-based ink using an organic solvent, particularly a hydrophobic organic solvent.

Since the above resin is blended in the ink of the present invention, the colored particles are coated with the resin after printing, and the colored particles are strongly fixed to the printing substrate (ink receiving layer) by the adhesive force of the coating resin. Accordingly, there is no peeling of the colored particles due to wear after printing and the color does not fade.
Further, when printing with the ink of the present invention, the colored particles are less likely to diffusely reflect visible light as a result of being coated with the resin having a low refractive index. Therefore, the printed image and the print are clear and the saturation is improved.

  Further, the resin preferably has an average molecular weight in terms of polyethylene of 2,000 to 100,000, particularly 5,000 to 30,000. When the average molecular weight of the resin is less than 2,000, curing of the resin after printing is delayed, and the colored particles and the resin may be liberated, or the colored particles may not be covered with the resin. The improvement effect cannot be expected. When the molecular weight of the resin exceeds 100,000, the viscosity of the ink increases and the ink jet nozzle may become clogged.

The concentration of the resin in the ink varies depending on the concentration of the colored particles, but is preferably in the range of 1 to 30% by weight, particularly 6 to 15% by weight. When the concentration of the resin in the ink is less than 1% by weight, the amount of the resin is too small to sufficiently cover the colored particles. On the other hand, if it exceeds 30% by weight, the ink viscosity may increase due to slight evaporation of the solvent or nozzle clogging may occur.
If the concentration of the resin in the ink is within the above range, the color is not lost, and a clear and excellent image can be obtained. Also, the amount of colored particles used can be reduced. Furthermore, even when the ink receiving layer has a pore size smaller than the colored particles and the colored particles cannot enter the pores of the ink receiving layer and are fixed to the surface of the receiving layer, the color is less likely to fade and the image is clear and colored. An excellent image can be obtained.

  In the ink of the present invention, the weight ratio (resin / colored particles) between the resin and the colored particles described later needs to be in the range of 2.5 to 25. When the weight ratio is less than 2.5, the amount of the resin is too small to cause discoloration or an effect of improving the saturation. On the other hand, even if the weight ratio exceeds 25, the above effect is further improved. When the number of colored particles is small, a sufficient coloring effect cannot be obtained. A preferable range of the weight ratio is 5 to 20, and a more preferable range is 8 to 20.

(2) Colored particles The colored particles contained in the ink of the present invention are not particularly limited as long as they are not dissolved in a resin, and conventionally known pigments such as carbon black, organic pigments, and inorganic pigments can be used.
As the organic pigment, monoazo pigments, xanthene pigments, triphenylmethane pigments, disazo pigments and the like are preferably used.
The concentration of such pigments in the ink varies depending on the purpose of printing, the type of printing substrate, printing equipment, etc., but is in the range of 0.05 to 10% by weight, particularly 0.5 to 5% by weight. It is preferable. When the concentration is less than 0.05% by weight, coloring tends to be insufficient. On the other hand, when the concentration exceeds 15% by weight, the viscosity of the ink may increase due to slight evaporation of the solvent or nozzle clogging may occur. is there.
Carbon black is usually used for oil-soluble inks, and those with sulfonates, carboxylates and quaternary amines as surface functional groups by surface modification can be suitably used for water-soluble inks. it can.

Furthermore, porous inorganic oxide fine particles containing dyes according to the prior application of the present inventors (Japanese Patent Application No. 11-241704) as colored particles can also be used in the same manner as the pigment. Since the porous inorganic oxide fine particles have both hydrophilic OH groups and hydrophobic organic groups, they are suitable for both water-based inks and oil-based inks.
Next, the porous inorganic oxide fine particles containing this dye and the production method thereof will be described in detail.
The porous inorganic oxide fine particles that can be used in the present invention are composite oxide fine particles comprising silica and an inorganic oxide other than silica. Examples of inorganic oxides other than silica include oxides of metals of 3A group, 3B group, 4A, 4B group, 5A group, 5B group, and 6A group of the periodic table or non-metallic elements. Are Al ₂ O ₃ , B ₂ O ₃ , TiO ₂ , ZrO ₂ , SnO ₂ , Ce ₂ O ₃ , P ₂ O ₅ , Sb ₂ O ₃ , MoO ₃ , WoO _3, etc., and complex oxides Examples thereof include TiO ₂ —Al ₂ O ₃ and TiO ₂ —ZrO ₂ .

Porous inorganic oxide fine particles, the molar ratio MO _X / SiO ₂ inorganic oxides other than silica to silica when expressed in MO _X is preferably in the range of 0.0001 to 0.2.
When the molar ratio is less than 0.0001, it does not become porous, and the occlusion of the dye described later is insufficient. In addition, when the molar ratio exceeds 0.2, the amount of silica is small, so the content of organic groups and amino groups introduced with the silica is reduced, the amount of occluded dye is reduced, and the adsorption capacity of the dye is reduced. As a result, stability and fixability are lowered, and when used as an ink, water resistance tends to be lowered. The porous fine particles may be silica having OH groups in part and inorganic hydroxides other than silica.

In the porous inorganic oxide fine particles, an organic group is directly bonded to a part of silicon. Examples of such organic groups include unsubstituted or substituted hydrocarbon groups having 1 to 10 carbon atoms, such as hydrocarbon groups, halogenated groups, epoxyalkyl groups, aminoalkyl groups, methacrylalkyl groups, mercaptoalkyl groups, and the like. Can do. Specifically, methyl group, phenyl group, isoptyl group, vinyl group, trifluoropropyl group, β- (3,4-epoxycyclohexyl) group, γ-glycidoxypropyl group, γ-methacryloxypropyl group, γ- In addition to the mercaptopropyl group, N-β (aminoethyl) γ-aminopropyl group, γ-aminopropyl group, N-phenyl-γ-aminopropyl group and the like can be mentioned.
Among the above organic groups, an amino group-substituted hydrocarbon group is preferable. Specifically, an aminopropyl group, N-β (aminoethyl) γ-aminopropyl group, γ-aminopropyl group, N-phenyl-γ-amino is preferable. A propyl group etc. are mentioned. Therefore, a preferred porous fine particle of the present invention has an amino group-substituted hydrocarbon group on the pore surface, and such an amino group has high affinity with a dye because of its cationic property, and is used as an ink component. Excellent water resistance when used.

  The amino group-substituted hydrocarbon group is preferably contained in 1 to 15 mmol in 1 g of porous inorganic oxide fine particles. When the amount of the amino group-substituted hydrocarbon group is less than 1 mmol / g, the stability and fixing property of the dye is lowered and the occlusion amount of the dye is also lowered. Depending on the case, the water resistance is lowered, and it may not be possible to print or record clearly. On the other hand, when the amount of the amino group-substituted hydrocarbon group exceeds 15 mmol / g, the amount of the amino group-substituted hydrocarbon group is too large, the formation of the silica skeleton is reduced, and the strength of the particles may be too low.

  The porous inorganic oxide fine particles occlude a dye via the amino group and / or organic group. In the present invention, occlusion means not only chemical adsorption or physical adsorption to an organic group such as an amino group, but also a state in which the porous inorganic oxide fine particles are held by affinity such as an amino group. As the dye, direct dyes, acid dyes, and basic dyes according to classification according to dyeing applications can be used. In the present invention, direct dyes and acid dyes are preferably used. In addition, according to the classification by chemical structure based on chromophore or chromogen which is another classification, use azo dye, anthraquinone dye, phthalocyanine dye, indigo dye, carbonium dye, nitro dye, quinoline dye, naphthoquinone dye, etc. Can do. According to another classification, dyes that are soluble in water or other solvents such as black, yellow, magenta, and cyan can be used.

Specific examples include the following dyes.
(A) C.I. I. Acid Yellow, (b) C.I. I. Acid Red, (c) C.I. I. Acid Blue, (d) C.I. I. Acid Black, (e) C.I. I. Food yellow, (f) C.I. I. Food red, (g) C.I. I. Food Black, (h) C.I. I. Direct yellow, (i) C.I. I. Direct Red, (j) C.I. I. Direct orange, (k) C.I. I. Direct Blue, (l) C.I. I. Direct Black, (m) C.I. I. Basic yellow, (n) C.I. I. Basic Red, (o) C.I. I. Basic Blue, (p) C.I. I. Basic Black, (q) C.I. I. Basic Green, (r) C.I. I. Triactive Black, (s) C.I. I. Reactive Yellow, (t) C.I. I. Reactive Red, (u) C.I. I. Reactive Blue, (v) C.I. I. Modern Blue, (w) C.I. I. Modern Red

The occlusion amount of the dye is preferably in the range of 0.017 to 0.5 g, and particularly preferably in the range of 0.1 to 0.5 g, per 1 g of the porous fine particles.
The above dye is occluded in the porous inorganic oxide fine particles based on the affinity between the organic group or amino group and the dye (molecule), and the occlusion amount is less than 0.017 g even if it is used as a printing ink, Some recording substrates cannot be printed or recorded clearly, that is, the coloring effect is insufficient. Further, even if the occlusion amount exceeds 0.5 g, improvement in printing and recording performance is not recognized, and conversely, since the amount of dye having low affinity with the porous fine particles increases, the water resistance tends to decrease.

A silica-based coating layer is preferably formed on the surface of the porous inorganic oxide fine particles. The silica-based coating layer includes a first silica-based coating layer having a thickness of 0.5 to 10 nm and a second silica coating layer having a thickness of 0.5 to 10 nm that is provided as necessary.
In the first silica-based coating layer, when the thickness is less than 0.5 nm, it is difficult to maintain the particle shape when removing the inorganic oxide other than silica from the core particles described later to make the porous material, and the thickness exceeds 10 nm. When the ratio of the silica-based coating layer is increased and the dye content is decreased, the coloring effect tends to be insufficient.

In the second silica coating layer, when the thickness is less than 0.5 nm, particles in which the dye is completely sealed cannot be obtained, and when the thickness exceeds 10 nm, the ratio of the silica coating layer only increases. For this reason, a coloring effect becomes inadequate when content of dye falls. Further, the second silica coating layer is preferably a dense film to the extent that the dye is not out of the particles from the viewpoint of water resistance.
The total value of the thickness of the first silica coating layer and the thickness of the second silica coating layer is preferably 20 nm or less. If it exceeds 20 nm, the coloring effect tends to be insufficient due to a decrease in the content of the dye, and it is necessary to increase the content of fine particles in order to obtain a sufficient coloring effect. In this case, however, the viscosity of the ink increases. This may cause clogging of the nozzle and wear of the nozzle due to fine particles.

It is preferable that an ultraviolet shielding coating layer is formed on the outermost surface of the porous inorganic oxide fine particles. The ultraviolet shielding coating layer is selected from the group consisting of oxides such as zinc oxide, cerium oxide, tin oxide, titanium oxide and zirconium oxide, and complex oxides thereof and hydroxides such as iron hydroxide. It is preferable to use seeds or two or more.
The thickness of the ultraviolet shielding coating layer is preferably 0.1 to 10 nm, particularly preferably 0.2 to 5 nm. When the thickness is less than 0.1 nm, the ultraviolet ray shielding effect or weather resistance such as ultraviolet ray resistance, oxidation resistance gas, acid resistance gas is not sufficiently obtained. On the other hand, when the thickness exceeds 10 nm, the weather resistance and the like may be further improved. In the same manner as in the case of the silica-based coating layer, the ratio of the coating layer increases and the content of the dye decreases, so that the coloring effect becomes insufficient.

  The average lasing diameter of the porous inorganic oxide fine particles is preferably 5 to 300 nm, particularly preferably 5 to 200 nm. When the average particle size is less than 5 nm, it is difficult to obtain porous fine particles having a large pore volume, and it is difficult to obtain fine particles having a high dye storage amount, and thus the coloring power becomes insufficient. When the average particle diameter exceeds 300 nm, the nozzles for inkjet are likely to be clogged, and fine particles may settle when the ink is not used or stored. In addition, depending on the printing substrate (recording sheet), it cannot be absorbed by the receiving layer, so that the adhesion may be lowered or the transparency may be lost.

(3) Other compounding agents If desired, the ink of the present invention may further contain a drying inhibitor, a penetrating agent, a pH adjuster, an antiseptic / antifungal agent, and a dispersant.
Hygroscopic organic or inorganic compounds are used as drying inhibitors, and organic hygroscopic agents are preferred because they do not aggregate due to salting out effects. Specifically, polyhydric alcohols such as diethylene glycol, polyethylene glycol, and glycerin And pyrrolidones such as N-methyl-2-pyrrolidone. Moreover, sodium lactate, dimethyl sulfoxide, etc. can also be used.
As penetrants to increase the permeation rate of ink and increase the permeation drying rate, strong basic substances such as caustic potash, anionic or cationic, nonionic surfactants, organic solvents such as glycol ethers (Aqueous organic solvent), low boiling aqueous organic solvents such as ethanol, isopropyl alcohol and the like.

As the pH adjuster, inorganic or organic alkali or inorganic or organic acid can be used. Specifically, potassium hydroxide, sodium carbonate, diethanolamine as alkali, phosphoric acid, ammonium sulfate, glycolic acid as acid, etc. Can be mentioned. In the case of oil-based inks, in particular, acetic acid, organic amines and the like can be suitably used.
As the antiseptic / antifungal agent, compounds such as sodium benzoate, potassium sorbate, and siabendazole can be used.

As the dispersant, a water-soluble polymer dispersant exhibiting surface activity can be used, and a preferable dispersant is a copolymer composed of a hydrophobic block and a hydrophilic block. Nonionic surfactants and anionic surfactants are particularly preferred.
In addition to the above additives, if necessary, the ink of the present invention may contain a chelating agent for preventing clogging of nozzles, an oxygen scavenger, an antifoaming agent, an ultraviolet absorber, and a conductivity imparting agent. In order to improve performance, urea or the like may be added.

(4) Water and / or an organic solvent is used as the solvent. In the case of a water-based ink, water is used as a main solvent. From the viewpoint of preventing nozzle clogging, it is preferable to use water excluding hard water components (polyvalent metal salts) in water. Moreover, low-boiling organic solvents, such as lower alcohols, such as methyl ethyl ketone, methanol, and ethanol, and acetate, can be mixed and used as needed.
In the case of oil-based ink, a low-boiling organic solvent such as methyl ethyl ketone, lower alcohols such as methanol and ethanol, and acetates can be used.

The contact angle of the ink of the present invention is preferably in the range of 10 ° to 40 °. When the contact angle is less than 10 °, liquid leakage may occur from the nozzles when printing is stopped, and when the contact angle exceeds 40 °, ink ejection may be delayed or the nozzles may be clogged. The contact angle is determined by dropping ink with a microsyringe on a flat and horizontal gold substrate, and using a contact angle meter (Kyowa Interface Chemical Co., Ltd .: CA-A type) 30 seconds to 1 minute after dropping. Can be measured.
The viscosity of the ink of the present invention is preferably in the range of about 1.2 to 10 centipoise. When the viscosity of the ink is less than 1.2 centipoise, liquid leakage may occur from the nozzle, and when the ink viscosity exceeds 10 centipoise, the nozzle may be clogged.

[Reference Examples 1 to 4]
Preparation of colored particle dispersion (1B) 1.5 g of styrene-acrylic acid-ethyl acrylate copolymer (average molecular weight 5000), 1 g of monoethanolamine, 81.5 g of pure water, and 5 g of diethylene glycol were mixed at 70 ° C. The resin was dissolved by stirring for a period of time. To this, 10 g of carbon black (manufactured by Mitsubishi Chemical Co., Ltd .: MCF88) and 1 g of isopropyl alcohol are added as colored particles. A liquid (1B) was obtained.

Preparation of colored particle dispersions (1Y), (1M), and (1C) CI direct yellow 1, CI food red 7, CI direct blue 2 were used as colored particles, respectively. Except for the above, colored particle dispersions (1Y), (1M), and (1C) were obtained in the same manner as the colored particle dispersion (1B). The average particle diameter of the colored particles in each of the obtained dispersions was measured, and the results are shown in Table 1.

Preparation of water- based ink (A) Polyester 905 (manufactured by Nippon Synthetic Chemical Co., Ltd., molecular weight = 15000, concentration 40% by weight) 45.0 g as a water-soluble resin in a mixed solvent of 30.0 g of water and 10.6 g of ethyl alcohol Disperse, and then disperse 12 g of the colored particle dispersion (1B), and then add 2.4 g of a surfactant (manufactured by Kyoyo Chemical Industry Co., Ltd .: Neupol E-194, concentration 40% by weight). A) was prepared.

Preparation of water-based inks (B), (C), (D) Inks (B), ( 1) and (1C) in the same manner as ink (A) except that colored particle dispersions (1Y), (1M), (1C) were used. C) and (D) were obtained. The contact angle and viscosity of each ink obtained were measured and the results are shown in Table 2.

Printing and Evaluation Using an ink jet printer (MJ-500C) manufactured by Epson Corporation, each ink (A) to (D) was used to print on a polyester film substrate coated with an ink receptor. In addition, the average pore diameter of the receiving layer formed by coating on a polyester film substrate was 15 nm.

The following evaluation was performed about the sample printed on the film. The evaluation results are shown in Table 2.
(1) The color fading print site was rubbed with a finger, and the change in image quality and the presence or absence of pigment adhering to the finger were examined and evaluated according to the following criteria.
○: No change in image quality and no pigment adhesion Δ: Some change in image quality and slight pigment adhesion ×: Some obvious change in image quality and pigment adhesion
(2) The water-resistant printed piece was immersed in water, and the bleeding and elution of the pigment were observed. The evaluation criteria are as follows.
◎: No bleeding is observed ○: Slight bleeding is observed Δ: Bleeding is clearly observed ×: Elution of pigment is observed

(3) Saturation C ^* was measured with a chromatographic spectrophotometer (Minolta Co., Ltd .: CM-2002). Chroma C ^* means that represents a C ^* in the L ^* C ^* h color system, the value, the bright enough to increase.
(4) The sharpness printing density was measured with a color reflectometer (manufactured by Nippon Denshoku Industries Co., Ltd .: KRD-2200). If the concentration is 1.2 or more, it can be used without any particular problem.

[Reference Example 5]
Preparation of water- based ink (E) 35.8 g of Polyester 905 (manufactured by Nippon Synthetic Chemical Co., Ltd., molecular weight = 15000, concentration 40% by weight) as a water-soluble resin was dispersed in a mixed solvent of 6.8 g of water and 5 g of ethyl alcohol. Then, 50 g of the colored particle dispersion (1M) prepared earlier was dispersed, and then 2.4 g of a surfactant (manufactured by Kyogo Chemical Industry Co., Ltd .: Neupol E-194, concentration 40 wt%) was added. Ink (E) was prepared. The obtained ink was subjected to measurement, printing and evaluation of the contact angle and viscosity in the same manner as in Reference Example 1, and the results are shown in Table 2.

[Reference Example 6]
Preparation of oil- based ink (F) As an oil-soluble resin, 39.9 g of alkyd resin (Dainippon Ink Co., Ltd., concentration 50% by weight) was dispersed in 39.1 g of xylene, and this was a dispersion of colored particles prepared previously. (1M) 21 g of oil was dispersed to prepare an oil-based ink (F). The obtained ink was subjected to measurement, printing and evaluation of the contact angle and viscosity in the same manner as in Reference Example 1, and the results are shown in Table 2.

[Reference Example 7]
Preparation of oil- based ink (G) 28.2 g of polyester polyol resin (Dainippon Ink Co., Ltd., concentration 40% by weight) as an oil-soluble resin was dispersed in 59.8 g of ethyl acetate, and colored particles prepared previously An oil-based ink (G) was prepared by dispersing 12 g of the dispersion liquid (1M). The obtained ink was subjected to measurement, printing and evaluation of the contact angle and viscosity in the same manner as in Reference Example 1, and the results are shown in Table 2.

[Example 1]
Preparation of colored particles (porous inorganic oxide particles containing dye)
(1) Preparation of core particle dispersion 36.1 g of γ-aminopropyltrimethoxysilane was mixed with 1444.4 g of 0.65 wt% aqueous sodium hydroxide solution and stirred at room temperature for 1 hour, and NH ₂ C ₃ H ₆ An aqueous solution of 1.5% by weight of a colorless and transparent partial hydrolyzate as SiO _3/2 was obtained.
Subsequently, a mixture of 20 g of silica sol having an average particle diameter of 5 nm and an SiO ₂ concentration of 20% by weight as seed particles and 380 g of pure water was heated to 80 ° C. The pH of the reaction mother liquor is 10.5, and the sodium silicate aqueous solution 900g as SiO ₂ of 1.5 wt% in uterine fluid, an aqueous solution 900g of the partial hydrolyzate concentration of 0.5 weight as Al ₂ O ₃ % 1800 g of a sodium aluminate aqueous solution was simultaneously added over 6 hours. Meanwhile, the temperature of the reaction solution was kept at 80 ° C. After completion of the addition, the reaction solution is cooled to room temperature and washed with an ultrafiltration membrane to disperse γ-aminopropyl group-containing SiO ₂ · Al ₂ O ₃ composite oxide fine particles (core particles) having a solid content concentration of 20% by weight. A liquid was obtained.
To 250 g of this core particle dispersion, 4750 g of pure water and 50 g of magenta dye (Solvent Red 145) (manufactured by Sumitomo Chemical Co., Ltd .: Sumiplast Red 3B) were added and stirred for a while, followed by concentrated hydrochloric acid (concentration 35.5 wt%). ) Was added dropwise to adjust the pH to 1.0, and dye occlusion and dealumination were performed.
Then, while adding 10 L of hydrochloric acid aqueous solution of pH 3 and 5 L of pure water, the dissolved aluminum salt was washed and removed using an ultrafiltration membrane, and concentrated to absorb a dye having a solid content concentration of 13% by weight. A dispersion (2M) of contained SiO ₂ / Al ₂ O ₃ composite oxide fine particles was obtained.

(2) Measurement of dye content in particles Printed with dye aqueous solutions (inks) with different known dye concentrations, and the reflection density was measured with a color reflection densitometer (manufactured by Nippon Denshoku Industries Co., Ltd .: KRD-2200). Measurement was made to determine the relationship between the dye concentration and the reflection density (calibration curve).
Next, printing using ink containing particles containing a dye, measuring the reflection density in the same manner, obtaining the dye concentration from the calibration curve, and calculating the dye in the particle from this, 0.29 g / 1 g fine particles.
(3) Determination of amino groups The amount of silica and inorganic oxides other than silica in the particles was determined by chemical analysis, and the amount of amino groups in the particles was calculated to be 5.9 mmol / 1 g particles.

Preparation of water- based ink (H) Polyester 960M (manufactured by Nippon Synthetic Chemical Co., Ltd., molecular weight: 7000, concentration 40% by weight) 19.7 g as a water-soluble resin in a mixed solvent of 59.5 g of water and 10.6 g of ethyl alcohol Dispersion solution of the colored particles (γ-aminopropyl group-containing SiO ₂ · Al ₂ O ₃ composite oxide fine particles occluded with a dye having an average particle size of 22 nm and a solid concentration of 13% by weight) 2M) 6.2 g was dispersed, and then 4 g of a surfactant (manufactured by Kyoyo Chemical Industry Co., Ltd .: Neupol E-194, concentration 40 wt%) was added to prepare ink (H). The obtained ink was subjected to measurement, printing and evaluation of the contact angle and viscosity in the same manner as in Reference Example 1, and the results are shown in Table 2.

[Example 2]
Printing and evaluation were performed in the same manner as in Example 1 except that the aqueous ink (H) obtained in Example 1 was used and printed on a polyester film substrate on which an ink receptor having an average pore diameter of 11 nm was formed. The results are shown in Table 2.

[Comparative Examples 1 to 4]
Preparation of water- based ink (I) Disperse in a mixed solvent of 67.4 g of water and 18.2 g of ethyl alcohol, and then disperse 12 g of the colored particle dispersion (1B), and then a surfactant (Kohaku Chemical Industry Co., Ltd.). 2.4 g of Neupol E-194 (concentration: 40% by weight) was added to prepare ink (I).
Preparation of water-based inks (J), (K), (L) Ink (J), (J) in the same manner as ink (I) except that colored particle dispersions (1Y), (1M), (1C) were used, respectively. K) and (L) were obtained. The obtained ink was measured, printed and evaluated for contact angle and viscosity, and the results are shown in Table 2.

[Comparative Example 5]
Printing and evaluation were performed in the same manner as in Comparative Example 3 except that the ink (K) obtained in Comparative Example 3 was used and printed on a polyester film substrate on which an ink receptor having an average pore diameter of 11 nm was formed. The results are shown in Table 2.

[Comparative Example 6]
Preparation of water- based ink Polyester 905 (manufactured by Nippon Synthetic Chemical Co., Ltd., molecular weight = 15000, concentration 40% by weight) 0.25 g as a water-soluble resin was dispersed in a mixed solvent of water 67.2 g and ethyl alcohol 10.6 g. Disperse 12 g of the colored particle dispersion (1M), and then add 2.4 g of a surfactant (manufactured by Kyoyo Chemical Industry Co., Ltd .: Neupol E-194, concentration 40 wt%) to obtain ink (M). Prepared.
The obtained ink was measured for contact angle and viscosity, printed and evaluated, and the results are shown in Table 2.

[Comparative Example 7]
Preparation of water- based ink As a water-soluble resin, 80 g of Polyester 905 (manufactured by Nippon Synthetic Chemical Co., Ltd., molecular weight = 15000, concentration 40% by weight) is dispersed in a mixed solvent of 3.4 g of water and 3 g of ethyl alcohol, and colored particles are dispersed therein. 12 g of a dispersion liquid (1M) was dispersed, and then 2.4 g of a surfactant (manufactured by Kyoyo Chemical Industry Co., Ltd .: Neupol E-194, concentration 40% by weight) was added to prepare an ink (N).
The obtained ink was measured for contact angle and viscosity, printed and evaluated, and the results are shown in Table 2.

[Comparative Example 8]
An oil-based ink (O) was prepared by dispersing 12 g of the colored particle dispersion (1M) prepared previously in 88 g of ethyl acetate. The obtained ink was subjected to measurement, printing and evaluation of the contact angle and viscosity in the same manner as in Reference Example 1, and the results are shown in Table 2.

[Table 1]
Tree fat deposition color particle child solvent resin / particles
Type content Type particle size content Type weight ratio
(wt%) (nm) (wt%)
Reference Example 1 PE905 18.0 1B 35 1.2 Water / Et 15.0
Reference Example 2 PE905 18.0 1Y 15 1.2 Water / Et 15.0
Reference Example 3 PE905 18.0 1M 20 1.2 Water / Et 15.0
Reference Example 4 PE905 18.0 1C 18 1.2 Water / Et 15.0
Reference Example 5 PE905 14.3 1M 20 5.0 Water / Et 2.86
Reference Example 6 Alkyd 20.0 1M 20 2.1 Xylene 9.5
Reference Example 7 PE / PO 11.3 1M 20 1.2 AcEt 9.4
Example 1 PE960M 7.9 2M 22 0.8 Water / Et 9.8
Example 2 PE960M 7.9 2M 22 0.8 Water / Et 9.8
-------------------------------------------------- --------
Comparative Example 1 None-1B 35 1.2 Water / Et-
Comparative Example 2 None-1Y 15 1.2 Water / Et-
Comparative Example 3 None-1M 20 1.2 Water / Et-
Comparative Example 4 None-1C 18 1.2 Water / Et-
Comparative Example 5 None-1M 20 1.2 Water / Et-
Comparative Example 6 PE905 0.1 1M 20 1.2 Water / Et 0.08
Comparative Example 7 PE905 32.0 1M 20 1.2 Water / Et 29
Comparative Example 8 None-1M 20 1.2 AcEt-

[Table 2]
Contact angle viscosity Discoloration Water resistance Vividness Saturation
(°) (cp) Reflectivity C *
Reference Example 1 25 2.3 ○ ◎ 1.5 1
Reference Example 2 24 2.0 ○ ◎ 1.6 40
Reference Example 3 20 2.1 ○ ◎ 1.3 52
Reference Example 4 20 1.9 ○ ◎ 1.5 27
Reference Example 5 18 1.4 △ ○ 1.7 47
Reference Example 6 30 2.4 ○ ◎ 1.6 50
Reference Example 7 25 3.5 ○ ◎ 1.6 51
Example 1 19 4.5 ○ ◎ 1.7 57
Example 2 20 3.0 ○ ◎ 1.7 56
-------------------------------------------------- -
Comparative Example 1 15 1.4 × × 1.0 1
Comparative Example 2 14 1.6 × × 0.9 36
Comparative Example 3 15 1.5 × × 1.0 45
Comparative Example 4 13 1.5 × × 0.9 20
Comparative Example 5 12 1.5 × × 1.0 48
Comparative Example 6 25 1.5 × × 1.0 41
Comparative Example 7 23 10.5 ○ ○ 1.5 55
Comparative Example 8 15 3.2 × × 1.0 42

Claims (8)

An ink containing 1 to 30% by weight of resin and 0.05 to 10% by weight of colored particles, wherein the colored particles are a composite oxide composed of silica and an inorganic oxide other than silica, and silica with respect to silica The inorganic inorganic oxide has a molar ratio (MO _x / SiO ₂ ) in the range of 0.0001 to 0.2 and is a porous inorganic oxide fine particle occluded with a dye, and 1 to 15 mmol of amino acid is contained in 1 g of the fine particle. An ink for inkjet recording, comprising a group-substituted hydrocarbon group, wherein the weight ratio of resin to colored particles (resin / colored particles) is in the range of 2.5-25.   The ink according to claim 1, wherein the amino group-substituted hydrocarbon group is an aminopropyl group.   The aminopropyl group is at least one selected from N-β (aminoethyl) γ-aminopropyl group, γ-aminopropyl group, or N-phenyl-γ-aminopropyl group. ink.   The ink according to any one of claims 1 to 3, wherein the dye occlusion amount is in a range of 0.017 to 0.5 g in 1 g of porous inorganic oxide fine particles.   The ink according to any one of claims 1 to 4, wherein the resin has an average molecular weight in terms of polyethylene in the range of 2,000 to 100,000.   A printing substrate obtained by inkjet recording using the ink according to claim 1, wherein the colored particles are fixed to the printing substrate by the adhesive force of the resin coated with the colored particles. A method for producing the ink according to claim 1,
After adding a dye to the core particle dispersion containing composite oxide fine particles composed of silica and inorganic oxides other than silica, a part of inorganic oxides other than silica is removed from the composite oxide fine particles to make it porous. In addition, a method for producing an ink for inkjet recording, wherein the porous inorganic oxide fine particles are occluded to form colored particles, and a resin is dissolved or dispersed in a dispersion of the colored particles. The method for producing an ink for inkjet recording according to claim 7, wherein the composite oxide fine particles are γ-aminopropyl group-containing SiO ₂ · Al ₂ O ₃ composite oxide fine particles.